Less css, nested attributes, :hover::after

The following works fine for me:

a {
    &:after {
        content:'a';
        background: red;
    }
    &:hover {
        &:after {
            background: blue;
        }
    }
}

My LESS-enabled editor, compiled that to:

a:after {
  content: 'a';
  background: red;
}
a:hover:after {
  background: blue;
}

Which does work.